JPH06105361B2 - Electrophotographic photoreceptor - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component.

[Prior art]

Conventionally, as an electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer containing an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide and silicon as a main component has been widely used. However, these are not always satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability and the like. For example, when selenium crystallizes, the characteristics as an electrophotographic photosensitive member deteriorate, and therefore it is difficult to manufacture, and selenium crystallizes due to heat, fingerprints, etc., and the performance as an electrophotographic photosensitive member deteriorates. In addition, cadmium sulfide and zinc oxide have problems in moisture resistance and durability.

In order to overcome the drawbacks of these inorganic photoconductors, research and development of organic photoconductors having a photosensitive layer containing various organic photoconductive compounds as main components have been actively conducted in recent years.

For example, Japanese Examined Patent Publication (Kokoku) No. 50-10496 describes an organic photoreceptor comprising a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not always satisfactory in sensitivity and durability.

In order to improve such a defect, attempts have been made to develop a high-performance organic photoconductor in which the carrier generation function and the carrier transport function are shared by different substances. Such a so-called function-separated type photoreceptor has been extensively researched because each material can be selected from a wide range and a photoreceptor having arbitrary performance can be prepared relatively easily.

As a result, various azo compounds have been developed and put into practical use as carrier generating substances. On the other hand, carrier-transporting substances are also disclosed in, for example, JP-A Nos.
No. 31, No. 53-27033, No. 55-52063, No. 58-65440
No. 58-198425, etc., a wide variety of substances have been proposed.

[Problems to be solved by the invention]

Some electrophotographic photoreceptors using the carrier transporting material as described above have relatively excellent electrophotographic performance, but have poor durability against light, ozone, or electrical load, and have poor performance after repeated use. Since it is stable and causes deterioration, etc., it does not sufficiently satisfy practical requirements, and it is desired to develop a carrier-transporting substance having an excellent carrier-transporting function and exhibiting stable performance for long-term use. Was there.

Further, in recent years, the demand for mounting an organic photoconductor on an electrophotographic copying machine capable of copying at higher speed has been increasing more and more, and development of a photoconductor having higher sensitivity and higher durability has been desired.

The present invention has been made to solve these problems and provide a photoreceptor having extremely high sensitivity and high durability.

[Means for solving problems]

The above problems have been solved by an electrophotographic photoreceptor having a photosensitive layer including a layer containing a hydrazone compound represented by the following general formula [I] on a conductive support.

General formula [I] In the formula, Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group,
Preferably, it represents a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, R ₁ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and preferably 1 to 8 carbon atoms. Substituted, unsubstituted alkyl group, substituted,
Represents an unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, R ₂ , R ₃ , R ₄ and R ₅ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, Represents a substituted amino group.

That is, in the present invention, the carrier transporting ability of the compound represented by the general formula [I] is utilized, and the carrier transporting of a so-called function-separated type electrophotographic photosensitive member is carried out by using separate substances for carrier generation and carrier transport. When used as a substance, it has excellent coating physical properties, excellent electrophotographic properties such as charge retention, sensitivity, residual potential, and little fatigue deterioration even after repeated use, and also with respect to heat, ozone, or light. It is possible to produce an electrophotographic photosensitive member that can exhibit stable characteristics.

Further, the carrier transporting material used in the present invention can be used alone or in combination of two or more kinds from the compounds represented by the general formula [I], and can be used in combination with other carrier transporting material. Good.

Specific examples of the carrier-transporting material represented by the above general formula [I] effective for the present invention include those having the following structural formulas, which limits the carrier-transporting material according to the present invention. Not a thing.

Exemplified compound The carrier-transporting substance is easily synthesized by a known synthesis method. For example, JP-A-57-64244 and 57-679.
The method described in No. 40 is referred to.

Synthesis Example (Synthesis of Exemplified Compound (I-1)) 18.2 g (0.1 mol) of the hydrazone ( 1 ) and 15.0 g (0.05 mol) of the aldehyde were dissolved in 300 ml of ethanol, 10 ml of acetic acid was added, and the mixture was heated under reflux for 5 hours. The mixture was allowed to cool and precipitated, and the result was collected by filtration, washed with ethanol, and then recrystallized from a mixed solvent of ethanol and methyl ethyl ketone.

Yield 23.8 g (75.8%) It was confirmed that the target compound was synthesized by observing a molecular ion peak of 629 in the FD-mass spectrum.

Next, as the carrier generating substance suitable for the present invention, an azo pigment is preferable, but in general, both an inorganic pigment and an organic pigment are used as long as they absorb visible light to infrared light and generate a free carrier. be able to. For example, in addition to inorganic pigments such as amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, and cadmium sulfide, organic pigments shown in the following representative examples may be used.

(1) Monoazo pigment, bisazo pigment, trisazo pigment,
Azo pigments such as metal complex salt azo pigments (2) Perylene-based pigments such as perylene anhydrides and perylene imides (3) Anthraquine derivatives, anthanthrone derivatives,
Polycyclic quinone pigments such as dibenzpyrenquine derivatives, pyranthrone derivatives, violanthrone derivatives and isobiolanthrone derivatives (4) Indigoid pigments such as indigo derivatives and thioindigo derivatives (5) Phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines (6) Carbonium pigments such as diphenylmethane pigments, triphenylmethane pigments, xanthene pigments and acridine pigments (7) Quinoneimine pigments such as azine pigments, oxazine pigments and thiazine pigments (8) Methine pigments such as cyanine pigments and azomethine pigments (9) Quinoline pigments (10) Benzoquinone and naphthoquinone pigments (11) Naphthalimide pigments (12) Perinone pigments such as bisbenzimidazole derivatives Carrier transport used in the present invention Since the substance itself has no film forming ability, it is combined with various binders to form a photosensitive layer.

As the binder used in the carrier generation layer and the carrier transport layer, any binder can be used, but it is preferable to use a hydrophobic electrically insulating film-forming polymer. Examples of such high molecular weight polymers include, but are not limited to, the followings.

(1) Polycarbonate (2) Polyester (3) Methacrylic resin (4) Acrylic resin (5) Polyvinyl chloride (6) Polyvinylidene chloride (7) Polystyrene (8) Polyvinyl acetate (9) Styrene copolymer resin (for example, styrene -Butadiene copolymer, styrene-methyl methacrylate copolymer, etc.) (10) Acrylonitrile-based copolymer resin (for example, vinylidene chloride-acrylonitrile copolymer, etc.) (11) Vinyl chloride-vinyl acetate copolymer (12) Vinyl chloride-vinyl acetate-maleic anhydride copolymer (13) Silicon resin (14) Silicon-alkyd resin (15) Phenolic resin (for example, phenol-formaldehyde resin, cresol-formaldehyde resin,
Etc.) (16) Styrene-alkyd resin (17) Poly-N-vinylcarbazole (18) Polyvinyl butyral (19) Polyvinyl formal (20) Polyhydroxystyrene These binders may be used alone or as a mixture of two or more kinds. Can be used.

As shown in FIGS. 1 and 2, the photoreceptor of the present invention comprises a carrier generating layer 2 containing a carrier generating substance as a main component and a compound of the present invention as a main component of a carrier transporting substance on a conductive support 1. A photosensitive layer 4 composed of a laminate with the carrier transport layer 3 contained therein is provided. As shown in FIGS. 3 and 4, the photosensitive layer 4 may be provided via an intermediate layer 5 provided on the conductive support 1. In this way, when the photosensitive layer 4 has a two-layer structure, an electrophotographic photosensitive member having the best electrophotographic characteristics can be obtained. Further, in the present invention, as shown in FIGS. 5 and 6, the photosensitive layer 4 formed by dispersing the fine particle carrier generating substance 7 in the layer 6 containing the carrier transporting substance as a main component is used as the conductive support. It may be provided directly on the intermediate layer 1 or via the intermediate layer 5.

Further, a protective layer 8 may be provided on the photosensitive layer 4 if necessary.

Here, when the photosensitive layer 4 has a two-layer structure, which of the carrier generation layer 2 and the carrier transport layer 3 is the upper layer is determined by whether the charging polarity is positive or negative. That is, when the negative charge type photosensitive layer is used, the carrier transport layer 3
Is an upper layer, because the carrier-transporting substance in the carrier-transporting layer 3 is a substance having a high hole-transporting ability.

In addition, the carrier generation layer 2 constituting the photosensitive layer 4 having a two-layer structure
Can be formed by the following method directly on the conductive support 1 or the carrier transport layer 3, or on the intermediate layer such as an adhesive layer or a barrier layer, if necessary.

(1) Vacuum evaporation method (2) Method of applying a solution in which a carrier generating substance is dissolved in an appropriate solvent (3) The carrier generating substance is made into fine particles in a dispersion medium by a ball mill, a sand grinder or the like, and if necessary,
A method of applying a dispersion obtained by mixing and dispersing with a binder.

The thickness of the carrier generating layer 2 thus formed is
The thickness is preferably 0.01 μm to 5 μm, more preferably 0.05 μm to 3 μm.

The thickness of the carrier transport layer 3 can be changed as necessary, but is usually preferably 5 μm to 30 μm. The composition ratio in the carrier transporting layer 3 is preferably 0.8 to 10 parts by weight of the binder with respect to 1 part by weight of the carrier transporting substance of the present invention, but a photosensitive layer in which fine particle carrier generating substances are dispersed. In the case of forming No. 4, it is preferable to use the binder within 5 parts by weight or less with respect to 1 part by weight of the carrier generating substance.

Further, when the carrier generation layer is formed as a dispersion type with a binder, it is preferable to use the binder in an amount of 5 parts by weight or less with respect to 1 part by weight of the carrier generation substance.

The layer structure of the photoreceptor of the present invention includes a layered structure and a single layer structure as described above, and any one of a carrier transport layer serving as a surface layer, a carrier generation layer, a single layer photosensitive layer or a protective layer, or a plurality of layers. The layer may contain one or more electron-accepting substances for the purpose of improving sensitivity, residual potential or reducing fatigue during repeated use.

The intermediate layer functions as an adhesive layer or a barrier layer, and in addition to the binder resin, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, casein, etc. are used.

As the electroconductive support 1 used in the construction of the electrophotographic photosensitive member of the present invention, the following are mainly used, but not limited thereto.

(1) Aluminum plates, metal plates such as stainless plates, and drum-shaped ones.

(2) A thin metal layer of aluminum, palladium, gold or the like provided on a support such as paper or a plastic film by laminating or vapor deposition.

(3) A layer of a conductive compound such as a conductive polymer, indium oxide or tin oxide is applied or vapor-deposited on a support such as paper or a plastic film.

The formation of constituent layers such as the carrier transport layer and the carrier generation layer according to the present invention includes vacuum deposition, sputtering, and CVD.
A vapor phase deposition method such as or a coating method such as dipping, spraying, blade, or roll method may be used.

The photoconductor of the present invention has the above-mentioned structure and is excellent in charging property, sensitivity property, and image forming property, as will be apparent from the examples described later. In particular, even when subjected to an anti-double transfer type electrophotographic system, fatigue deterioration is small and durability is excellent.

〔Example〕

Examples of the present invention will be specifically described below, but the embodiments of the present invention are not limited thereto.

Example 1 A vinyl chloride-vinyl acetate-maleic anhydride copolymer "S-REC MF-10" (manufactured by Sekisui Chemical Co., Ltd.) was formed on a conductive support obtained by vapor-depositing aluminum on a polyester film.
An intermediate layer having a thickness of 0.1 μm.

In addition, 1,2 parts by weight of dibromoanthanthrone "Monolight Red 2Y" (manufactured by ICI) and 0.5 parts by weight of polycarbonate resin "Panlite L-1250" (manufactured by Teijin Kasei) represented by the following structural formulas -A liquid which was mixed with 100 parts by weight of dichloroethane and dispersed in a ball mill for 24 hours was applied so that the film thickness after drying would be 1 µm to form a carrier generation layer.

In addition, the exemplary compound (I-1) as a carrier transport substance
7.5 parts by weight and polycarbonate resin "Panlite L-125"
A liquid obtained by dissolving 10 parts by weight of 0 "in 80 parts by weight of 1,2-dichloroethane was applied so as to have a film thickness after drying of 16 μm to form a carrier transport layer, thereby preparing an electrophotographic photoreceptor of the present invention. .

About this electrophotographic photoreceptor Electrostatic copying paper test device "SP-
428 ”(Kawaguchi Denki Seisakusho) was used to measure electrophotographic characteristics by a dynamic method.

That is, the photosensitive layer surface of the photoconductor is 5
The surface potential V _A when charged for a second, and then the amount of exposure required to attenuate the surface potential from −600 V to −100 V by irradiating the light from a tungsten lamp so that the illuminance on the photoconductor surface becomes 3.5 lux ( Sensitivity) ▲ E ⁶⁰⁰ ₁₀₀ ▼, and 30lux
・ Surface potential (residual potential) V after irradiation with exposure amount of sec
_R was calculated respectively.

The same measurement was repeated 100 times. The results are as shown in Table 1.

Comparative Example (1) A comparative photoconductor (1) was prepared in the same manner as in Example 1 except that the hydrazone derivative represented by the following structural formula was used as the carrier-transporting substance, and the same measurement as in Example 1 was performed. .

The results are shown in Table 1.

As is clear from the above results, the electrophotographic photosensitive member of the present invention of Example 1 is significantly superior to the photosensitive member of Comparative Example (1) in sensitivity, residual potential characteristics and stability of repetition.

Examples 2 to 10 Exemplified compounds (1-2) and (I-
4), (I-6), (I-8), (I-10), (I-1
2), (I-14), (I-16) and (I-18) were used to prepare an electrophotographic photoreceptor of the present invention in the same manner as in Example 1. These electrophotographic photosensitive members were measured in the same manner as in Example 1. The results are shown in Table 2.

Example 11 1 part by weight of a bisazo pigment represented by the following structural formula as a carrier-generating substance on a conductive support formed by laminating an aluminum foil on a polyester film, and a polymethylmethacrylate resin "Dynar BR-80" (Mitsubishi Rayon Co., Ltd.) 0.5 parts by weight) was added to 100 parts by weight of 1,2-dichloroethane, and a liquid dispersed by a sand grinder for 4 hours was applied so that the film thickness after drying was 0.4 μm to form a carrier generation layer.

Next, exemplary compound (I-3) as a carrier transporting material 7.
5 parts by weight and polycarbonate resin "Panlite K-130"
0 ”(manufactured by Teijin Kasei) and 10 parts by weight of 1,2-dichloroethane 10
A liquid dissolved in 0 part by weight was applied so that the film thickness after drying would be 15 μm, and a carrier transport layer was formed to prepare an electrophotographic photoreceptor of the present invention.

When this electrophotographic photosensitive member was measured in the same manner as in Example 1, the results shown in Table 3 were obtained.

Comparative Example (2) A comparative photoconductor (2) was prepared in the same manner as in Example 11 except that the hydrazone derivative represented by the following structural formula was used as the carrier-transporting substance. When this comparative photoconductor was measured in the same manner as in Example 1, the results shown in Table 3 were obtained.

As is clear from the above results, the electrophotographic photosensitive member of the present invention of Example 11 is remarkably excellent in sensitivity, residual potential and stability of repetition as compared with the comparative photosensitive member.

Example 12 A vinyl chloride / vinyl acetate / maleic anhydride copolymer “S-REC MF-10” having a thickness of 0.1 μm on a conductive support formed by vapor-depositing aluminum on a polyester film.
m intermediate layers were provided.

Further, 1 part by weight of a bisazo pigment represented by the following structural formula as a carrier-generating substance and 0.5 part by weight of a polycarbonate resin "Panlite K-1300" were added to 100 parts of tetrahydrofuran.
In addition to parts by weight, a liquid dispersed by a ball mill for 24 hours was applied so that the film thickness after drying would be 0.4 μm to form a carrier generation layer.

Then, an exemplary compound (1
-5) A solution prepared by dissolving 7.5 parts by weight and 10 parts by weight of the polycarbonate resin "Panlite K-1300" in 100 parts by weight of tetrahydrofuran was applied so that the film thickness after drying would be 17 μm, and the electrophotographic photosensitive material of the present invention. Created the body.

When this electrophotographic photosensitive member was measured in the same manner as in Example 1, the results shown in Table 4 were obtained.

Example 13 An electrophotographic photoreceptor of the present invention was prepared in the same manner as in Example 12 except that the bisazo pigment represented by the following structural formula was used as the carrier-generating substance.

When this electrophotographic photosensitive member was measured in the same manner as in Example 1, the results shown in Table 4 were obtained.

Example 14 Vinyl chloride-on a cylindrical aluminum drum having a diameter of 80 mm
Vinyl acetate-maleic anhydride copolymer "S-REC MF-
An intermediate layer of 10 "having a thickness of 0.1 µm was applied by a dipping method.

Dibromoanth Anthron "Monolight Red on it
1 part by weight of 2Y and polycarbonate resin "Panlite L-
1250 parts by weight and 1,2-dichloroethane (100 parts by weight) were mixed and dispersed by a ball mill for 24 hours to apply a liquid, which was applied by a dipping method to form a carrier generation layer having a film thickness of 1 μm.

Furthermore, an exemplary compound (I-
1) 7.5 parts by weight and a polycarbonate resin “Z-200” represented by the following structural formula (Mitsubishi Gas Chemical Co., Ltd. 10 parts by weight and 80 parts by weight of 1,2-dichloroethane were applied to the solution by the same dipping method to obtain a film thickness of 17
A carrier transport layer having a thickness of μm was formed to prepare an electrophotographic photoreceptor of the present invention.

This electrophotographic photoconductor is an electrophotographic copying machine "U-Bix1550M
When the image was copied and mounted on the "R", a copy image that was faithful to the original image, high in contrast, and excellent in gradation was obtained. Even if this was repeated 50,000 times, a copied image similar to the initial one was obtained.

Comparative Example (3) A comparative photoconductor (3) was prepared in the same manner as in Example 14 except that the hydrazone derivative represented by the following structural formula was used as the carrier-transporting substance.

When an image was copied on this comparative photoconductor in the same manner as in Example 14, a good copy image was obtained in the initial stage as in Example 14, but fogging started to be noticeable around 20,000 copy, and at 20,000 copy, Only an image with a lot of fog and a lowered contrast was obtained.

Example 15 A vinyl chloride-vinyl acetate-maleic anhydride copolymer `` S-REC MF-10 '' on a conductive support obtained by laminating an aluminum foil on a polyester film.
A 1 μm intermediate layer was provided.

Then, an exemplary compound (I
-7) 7.5 parts by weight and 10 parts by weight of the polycarbonate resin "Panlite L-1250" dissolved in 80 parts by weight of 1,2-dichloroethane are applied so that the film thickness after drying is 15 µm and the carrier is transported. Layers were formed.

Furthermore, a carrier generating substance 1 represented by the following structural formula
Examples of the compound (I-
7) 1.5 parts by weight, polycarbonate Resin "Panlite L-1250" (2 parts by weight) is added to 100 parts by weight of 1,2-dichloroethane, and a dispersion is applied by a ball mill for 24 hours, and a carrier generating layer having a film thickness after drying of 3 μm is provided. An electrophotographic photoconductor of was prepared.

This electrophotographic photosensitive member was measured in the same manner as in Example 1 except that the charged voltage was changed to +6 kv, and the results shown in Table 5 were obtained.

Comparative Example (4) A comparative photoconductor was prepared in the same manner as in Example 15, except that the hydrazone derivative represented by the following structural formula was used as the carrier-transporting substance.

When this comparative photoreceptor was measured in the same manner as in Example 15, the results shown in Table 5 were obtained.

As is clear from the above results, the electrophotographic photosensitive member of the present invention has extremely excellent characteristics in sensitivity and stability of repetition as compared with the comparative photosensitive member.

Example 16 A 0.1 μm-thick intermediate layer made of a vinyl chloride-vinyl acetate-maleic anhydride copolymer “S-REC MF-10” was provided on a polyester film on which aluminum was vapor-deposited.

1,2-dichloroethane 10 parts by weight of 1 part by weight of a bisazo pigment represented by the following structural formula and 0.5 part by weight of a polycarbonate resin "Panlite L-1250" as a carrier transporting substance were further added.
In addition to 0 parts by weight, a liquid dispersed by a ball mill for 24 hours was applied so that the film thickness after drying would be 0.3 μm to form a carrier generation layer.

Furthermore, an exemplary compound (1-
9) 7.5 parts by weight of polycarbonate resin "Panlite K
-1300 "10 parts by weight dissolved in 100 parts by weight of 1,2-dichloroethane is applied so as to have a film thickness after drying of 16 μm to form a carrier transporting layer to prepare an electrophotographic photoreceptor of the present invention. did.

When this electrophotographic photosensitive member was measured in the same manner as in Example 1, the results shown in Table 6 were obtained.

Example 17 1 part by weight of a carrier-generating substance represented by the following structural formula and a polyester resin “Vylon 200” (Toyobo Co., Ltd.) on a polyester film on which aluminum was vapor-deposited 0.5 parts by weight and 100 parts by weight of 1,2-dichloroethane were added, and a liquid dispersed by a ball mill for 24 hours was applied to a thickness of 0.5.
A μm carrier generation layer was formed.

Furthermore, an exemplary compound (I-
11) Represented by 4.0 parts by weight and the following structural formula A hydrazone derivative (A) (3.5 parts by weight) and a polycarbonate resin "Panlite K-1300" (10 parts by weight) dissolved in 100 parts by weight of 1,2-dichloroethane are applied to a thickness of 15 µm.
The carrier transporting layer was formed to prepare the electrophotographic photosensitive member of the present invention.

When this electrophotographic photosensitive member was measured in the same manner as in Example 1, the results shown in Table 7 were obtained.

Comparative Example (5) A comparative photoconductor (5) was prepared in the same manner as in Example 17, except that 7.5 parts by weight of the hydrazone derivative (A) used in Example 17 was used as the carrier-transporting substance.

When this comparative photoreceptor was measured in the same manner as in the example, the results shown in Table 7 were obtained.

As is clear from the above results, the electrophotographic photosensitive member of the present invention is remarkably excellent in sensitivity, residual potential characteristics and stability of repetition as compared with the comparative photosensitive member.

[Brief description of drawings]

1 to 6 are cross-sectional views showing examples of the mechanical constitution of the photoconductor of the present invention. 1 ... Conductive support 2 ... Carrier generation layer 3 ... Carrier transport layer 4 ... Photosensitive layer 5 ... Intermediate layer 6 ... Layer containing carrier transport material 7 ... Carrier generation material

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a conductive layer and a photosensitive layer containing at least one hydrazone compound represented by the following general formula [I]. General formula [I] [Wherein Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, R ₁ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or R ₂ , R ₃ or R ₄ , R ₅ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a substituted amino group. ]